<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
var b=1;
var c=2;
var d=3;
var e=4;
           var a=prompt('请输入您要的操作:\n 1.存钱\n 2.取钱\n 3.显示余额\n 4.退出')
          if (b ==1 ) {
              prompt('请输入你要存的钱')
          }
    </script>
</body>
</html>